1. Field of the Invention
The present invention relates to a communication system comprising a data terminal, a wireless communication device, and data transmission means for setting up a local data transmission connection between the data terminal and the wireless communication device, wherein the data transmission means comprise the data transmission means of the data terminal and the data transmission means of the wireless communication device, and the data terminal comprises means for running application software, an application programming interface, means for controlling the data transmission means of the data terminal, and a first connection interface for data transmission between the application and the application programming interface. Furthermore, the invention relates to a data terminal to be used in a communication system comprising also a wireless communication device, and data transmission means for setting up a local data transmission connection between the data terminal and the wireless communication device, wherein the data transmission means comprise the data transmission means of the data terminal and the data transmission means of the wireless communication device, and the data terminal comprises means for running application software, an application programming interface, means for controlling the data transmission means of the data terminal, and a first connection interface for data transmission between an application and the application programming interface. Moreover, the invention relates to a method for data transmission between a data terminal and a wireless communication device, in which method a local data transmission connection is set up between the data terminal and the wireless communication device, the data terminal is equipped with an application programming interface and the data transmission means for the data terminal, and an application software is run in the data terminal, wherein data is transmitted between the application and the application programming interface via the first connection interface.
2. Brief Description of Related Developments
In a way known as such, a modem is used for coupling a data terminal and telecommunication network to enable data transmission between the data terminal and the telecommunication network. The model performs e.g. the adapting of signals transmitted from the data terminal to the telecommunication network into a suitable format and, correspondingly, the adapting of signals received from the telecommunication network into a format intelligible to the data terminal.
Two data terminals can communicate with each other via a telecommunication network. In this communication, a known data transmission protocol is generally used to secure the operation and the reliability of the connection. One example of a data transmission protocol is error correction, for which the transmitting data terminal supplements the data to be transmitted with check-up characters according to a standard applied. By comparing the received data with the check-up characters, the receiving data terminal can deduce whether errors are contained in the data transmission.
With the increase in wireless communication, also wireless communication devices are introduced as part of data transmission systems, wherein such a wireless communication device is arranged in a data transmission connection with a data terminal. Thus, the wireless communication device takes care of the adapting between the data terminal and the wireless communication network. Such a wireless communication device used can be e.g. a mobile phone according to the GSM mobile communication system, equipped with means for coupling to the data terminal.
In the first generation of such wireless communication devices, the data terminal was coupled typically with a wire by means of a serial bus, wherein a connecting cable made for this purpose was coupled between the wireless communication device and the data terminal. Particularly in wireless communication devices, the structure of the connection can vary between different manufacturers and even between different models by the same manufacturer; consequently, a connecting cable of a certain kind, suitable for the model in question, had to be acquired for each wireless communication device. For eliminating this drawback, also other communication systems have been developed between the wireless communication device and the data terminal. As an example, a wireless connection based on infrared data transmission should be mentioned in this context. For applying this connection, the IrDA standard (Infra-red Data Association) has been drawn up, and this IrDA standard is observed by several manufacturers in their own wireless communication devices in which such an option for infrared connection is implemented. A wireless communication system based on radio communication is also under development, particularly to meet the needs of data transmission in short distances, such as for arranging a data transmission connection between a wireless communication device and a data terminal. Thus, the wireless communication device and the data terminal each have a separate radio transmitter/receiver, whereby the wireless communication device and the data terminal can communicate with each other. Also other techniques are known for arranging a wireless data transmission connection between two devices, e.g. an inductive connection.
Also, wireless communication devices are known which are formed as a connection card to be connected to the data terminal. One such a connection card to be mentioned is the so-called PCMCIA connection card (Personal Computer Memory Card Association). Such a card-format wireless communication device can be used particularly in the case of portable computers to implement a wireless data transmission connection via a mobile communication network to another data terminal. For connecting the connection card, the data terminal is equipped with a card connection, through which e.g. the operating voltages and the required signals are transmitted to the connection card.
In addition to the fact that the wireless communication device and the data terminal use data transmission means according to the same data transmission method, information must be converted to a format compatible with this data transmission method in the wireless communication device and in the data terminal. The data terminal, such as a so-called personal computer PC, is provided with a device driver for the adapting between the hardware and the software in the data terminal. The actual information to be transmitted is generated in an application software, e.g. in a terminal emulator. This application program transmits the information to be transmitted to an application programming interface API, where the information is converted to a format complying with the data transmission method to be used, e.g. into a format to be transmitted via a serial port to a serial bus, or, when infrared connection is used, into a format compatible with this connection method. From the application programming interface, the information is transmitted to the corresponding device driver which controls the actual data transmission means. One such arrangement of prior art is shown in a reduced block chart in the appended FIG. 1. In practical applications, these blocks shown in FIG. 1 are implemented at least primarily in the software, which is known as such.
In a corresponding manner, the means required for using the local data transmission connection are implemented in the wireless communication device, wherein the wireless communication device can transmit information conveyed via the local data transmission connection to a mobile communication network and, correspondingly, information conveyed via the mobile communication network to the local data transmission connection.
If the wireless communication device is provided with such local data transmission means, it is usually also provided with the required software integrated already at the manufacturing stage.
The data terminal can have several different local data transmission methods available, wherein the data terminal is equipped with the respective device drivers or the like for controlling the data transmission means. Moreover, the operations required for different types of data transmission methods must be implemented in said application programming interface API, preferably in the mobile phones application programming interface MPAPI. For example, if a wired serial-format data transmission connection, an infrared data transmission connection and a radio data transmission connection are available in the data terminal, this mobile phones application programming interface must have means for transmitting information between the data transmission means and the application for all these different methods of data transmission. A drawback in such an arrangement is that e.g. upon adding one new method of data transmission or changing the properties of a data transmission method already implemented, the modifications must be directed to this whole MPAPI interface. Thus, the work involved in these changes increases substantially, and moreover, the maintenance of such an arrangement requires a lot of resources. Also, the possibility of errors in such a way of implementation is great.
The way of coupling the wireless communication device to the data terminal affects the protocol used in the data transmission connection. For example, in a wired, serial-format data transmission connection, the data transmission protocol can be an asynchronous or synchronous serial-format data transmission protocol. In a corresponding manner, in an infrared connection, the transmission of various messages is typically used.
In such an MPAPI interface according to prior art, this MPAPI interface communicates with the corresponding device driver which transmits the messages further to the wireless communication device. Thus, the MPAPI interface takes care of dividing the messages to be transmitted into suitable elements (packets), buffering, and other corresponding basic operations. Typically, these operations are not similar in different data transmission methods, wherein the structure of the MPAPI interface can become very complex, if many different data transmission methods are implemented in this MPAPI interface.
It is a purpose of the present invention to present a data transmission system in which the above-mentioned drawbacks are eliminated to a great extent. This data transmission system is based on the idea that a data adapter is provided between the MPAPI interface and the device drivers to take care of the required conversions between the MPAPI interface and the device driver. The data transmission system according to the present invention is characterized in that the data transmission system comprises also a data adapter, a second connection interface for data transmission between the application programming interface and the data adapter, and one or several media interfaces for data transmission between the data adapter and the data transmission means of the data terminal. The data terminal according to the present invention is characterized in that the data terminal comprises also a data adapter, a second connection interface for data transmission between the application programming interface and the data adapter, and one or several media interfaces for data transmission between the data adapter and the data transmission means of the data terminal. Furthermore, the method according to the present invention is characterized in that in the method, also a data adapter is provided, wherein information is transmitted between the application programming interface and the data adapte, and information is transmitted between the data adapter and the data transmission means of the data terminal via one or several media interfaces.
Using the present invention, significant advantages are achieved with respect to solutions of prior art. In the data transmission system of the invention, the MPAPI interface can be maintained substantially the same also in a situation when a data terminal is supplemented with new local data transmission means. The required modifications are thus implemented in the data adapter according to the invention, wherein the maintenance of the system is considerably simpler and the possibilities of errors are reduced when compared with the arrangement of prior art. Moreover, the modification of the data adapter requires no information on the internal method of implementation of the MPAPI interface but only on the interface between the data adapter and the MPAPI interface.